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What is the A350's procedure for stained cockpit windows?
Recently I read of this Ethiopian B737 incident at Dire Dawa on Jan 9th 2020. The aircraft flew through a swarm of locusts, which didn't cause any significant damage, but it rendered the cockpit windows completely opaque. So it clearly can happen.
Now on most aircraft, including B737 from that incident, the cockpit side windows can be opened and provide enough forward visibility to land the airplane from basically any available instrument approach.
However, A350 does not have any opening window that could be used, and Cat IIIB approaches that can be executed without any visibility are much rarer than just any instrument approach, so none may be available in range.
So what would the pilots do?

See also BA flight 9 for a successful landing with largely opaque windows.

It would depend on how badly the side windows were rendered opaque.  If the Capt's side window still had enough clarity to make out the runway boundary during the roundout and flare, that would be enough.
You can land airplanes fine without being able to see directly forward as long as you can see out the sides.   When you fly a taildragger from the back seat, which is normal in taildraggers you solo from the back, like J-3 Cubs and most biplanes, you land all the time without being able to see a damn thing in front of you since the nose blocks everything about 60 degrees each side of the nose and you land using your peripheral vision.  So that's not really a problem for a decently skilled captain.
If the side windows were as opaque as the windshield, you have a problem and you'd have to try to whatever you can think of.  I'd go try to find some cloud and see if I can get enough moisture on the glass for the wipers to work.  Or whatever off the wall ideas any of my crew can think of.
And if none of that works, well you do the best you can, performing your own homebrew Cat IIIB landing and hope you can stay between the runway lights.  You can just stay on the localizer right down to the flare and control the flare based on rad alt, so the really big challenge is really just staying centered on the runway.  You might try having a crew member sit behind you against the rear side window if that had visibility, where they can see the runway edges, and verbally call out left/right corrections through the touchdown and rollout.
If it was late enough in the day I would probably elect to delay landing until dusk because the runway lights would show up way better though the frosted glass effect in the dark, well enough at least to be able to stay between them.  I would say that as long as you can make out the runway lights, you'd be good.
Even during the day, depending on how bright the day was with cloud conditions etc, you might find the runway lights cranked up to max intensity could be made out through the goo, good enough to be able to land and stay on the runway.  So I don't think the bug mooshed windows are a death sentence, but you'd be earning your 6 figure salary for sure.

If you can follow the ILS to minimums, perhaps someone (preferrably an experienced pilot) on the ground might be able to talk you down the rest of the way.  I have read of it being done, I think.

Of course there is also the case when the windows are fine, but the visibility is below minima everywhere in range, like this accident in Jaipur on Jan 5th 2014 and the follow-up incident. But if someone can advise from the ground, it is certainly safer than those.

I am not sure if this applies to modern jets, but pilots of the past were sometimes landing "sideways" by using https://en.wikipedia.org/wiki/Slip_(aerodynamics). That provided some view from the side window.
I believe one example of that could be found in "Fate is the Hunter" by Ernest Gann.
Also general aviation pilots sometimes use this technique if the windshield is iced over.


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Can doppler radar be used to detect stealth aircraft by focusing on the characteristic flow field instead of the aircraft itself?
Any aircraft traversing through the air would impart velocity, pressure, and temperature gradients to the surrounding air, then there are some phenomenon which are unique to all winged bodies such as wing tip vortices. These gradients do not occur naturally and develop in a very distinct manner (say in a straight line)
If there is a doppler radar which is attuned to ignore all naturally occurring gradients and only look for gradients that have man made origins then it can tell that there is something flying through the space. It doesn't even need to be trained on stealth aircraft as it is not even looking at the aircraft but the flow field around it and such data can be readily generated by any conventional fighter jet.
If it is working in conjunction with "regular" radar and it sees something that the regular radar doesn't then it implies presence of a stealth aircraft and that area in space can be investigated with more energy and other sensors.
Also, why can't a surface-to-air missile be launched and be guided by such a radar? After all, it can clearly determine how the source of disturbances is traversing in space because disturbances follow the source (duh!), when the missile reaches close to the aircraft, hopefully its own radar would be able to lock on its target.

To a limited extent, yes, it's possible to detect the air disturbances left by aircraft. This NASA article studies the radar reflectivity of vortex wakes exhaustively. It's being proposed as a safety measure for civil aviation, to avoid wake turbulence incidents.
This is a 2000s follow-up to the 1992 Gilson study. Gilson is much easier to read, but was more focused on assessing wake detectability with present sensors than on looking for the best one.

Besides the wake vortex itself, the higher temperature and humidity of engine exhaust also contribute to radar detectability to a small extent. All this makes building a completely invisible aircraft physically impossible. But this is not likely to be the best method for detecting stealth aircraft.
The newer studies against a small target have measured a typical wake RCS of about -62 dBsm, but it goes higher with optimized equipment.

This is smaller than most stealth aircraft' RCS itself (-40 to -20 dBsm). But it scales with size, as can be seen in the Gilson study, where the C-5A produced up to -30 dBsm.
Jet fighters are in between the C-5A and the test target in size. Wake RCS also cannot be defeated by any kind of stealth shaping, RAM, or RAS. As long as it's flying, an aircraft's wake will be more detectable the larger and the faster it is. The wake is also persistent, greatly improving the sensitivity gains from continuous scanning.
But the utility of this can be overestimated without accounting for the finer points of how radar and stealth works.

First of all, an air-to-air missile can be launched without a guiding radar at all, as a "mad dog". It will acquire a stealth aircraft at a closer, but still usable range.
Second, radars can be made significantly more sensitive and selective, if you use a narrow beam at low scan speed and know where to point it.
Third, the radar cross-section of an airplane is not a static number. It's a complex 4D function, which depends non-linearly on the angle of observation and radar frequency. Add flight controls position and polarization, then it gets really complex.

The RCS of a fighter can be very roughly visualized like this:

Some combination of the 3 factors above is how the Serbs have shot down an F-117 using only an S-125 - a 1961 system, predating Ufimtsev's seminal work on radar stealth by a year, so clearly not meant for the job.
Now to the fourth factor: the role of a radar isn't simply to detect targets. It's to detect, classify, measure their range, velocity and motion vector, track, and optionally illuminate them for missile lock.
There are many ways to detect the presence of a stealth aircraft. Multistatic radars, satellite photos, good old espionage. None of them, however, give the tracking ability of a direct radar beam.
Wake tracking is one more way to detect aircraft, but it won't be very effective for tracking them. This is because the wake's RCS increases with time, making older detection events more visible than new ones.
For tracking, most systems would still have to rely on a traditional radar. Can it do it? Here's the modeled X-band RCS for an F-35:

A stealth aircraft looks to a radar a bit like a disco ball: its reflections are all specular and concentrated in specific directions. Except, unlike a disco ball, the mirrors are arranged such as not to hit the observer's eye as often, and are tinted dark by using RAM.
So how does it look to the pilot, say if it's an F-14 trying to detect and track an F-22?
It's not a complete absence of signal. Due to the many spikes on the charts, the stealth aircraft will still be detected, even by an old, pre-stealth radar. But it will look like intermittent blips on the screen, rather than a continuous track. The F-14 pilot will not be able to set his systems to track the aircraft, and will have to rely on a mad dog launch or a visual to have a shot at it.
For older radars, it wasn't trivial to get a track on a regular aircraft. They aren't designed to deal with stealth ones, which give occasional blinks rather than a solid reflection. While at that, many countries don't even have F-14 level tech.
Modern radar systems are nowhere near as stealth-naive as the S-125 or the AWG-9. It took the Soviets a decade to realize its importance, but the development of counter-stealth technology started once they learned of the F-117.
These include IRST systems, against which radar stealth has no effect, very high output radars, which counter it directly, but not by much, and renewed development of radars functioning outside the X-band, where stealth is much less effective. Here is the statistically modeled RCS of the F-22 at VHF, namely 230 MHz:

It's still pretty good, still better than a 4th-gen fighter, like in the charts above. However, this frequency band is only generally used by ground radars, and then only non-NATO ones.
However, the US has installed a dual-band radar in its two newest warships, and Russia in its latest fighter, the Su-57. Dual-band radars are more effective against stealth than disjointed sensors, being able to focus the high-frequency beam to track the blips spotted by the low-frequency one. Stealth and counterstealth are complementary games that both sides are playing now.
Where an F-14 pilot would only see occasional radar blips, 4.5-5 gen fighters can at least target a stealth aircraft. The track will be inaccurate and much jumpier than usual, but better than nothing. IRST can also reach over 100 km by now, but it's more weather-dependent than radar.
In high-intensity warfare, with ground radars, IADS, AEW, stand-off jamming, countermeasures, many flights in the air, it's not just a jousting duel. Both stealth and non-stealth aircraft can be detected or avoid detection, and stealth acts like setting your opponent's radar back by 20 years.
But it's not set back by 100 years. Successful covert missions are much more achievable with a stealth aircraft, but still require planning and avoidance.

Summary: there are easier ways to detect and track stealth aircraft than chasing their wake. The best-case RCS of an F-22 is still higher than that of its wake, at least in subsonic flight. But if radar and IR stealth were to improve greatly, this could be useful.
There's inconclusive evidence on whether wake detection might work better with higher-frequency radars. These potentially allow for stealth detection with much smaller sensors. However, wake tracking is not useful for missiles, since the wake's signature gets larger as it spreads - like a built-in chaff dispenser.

"A stealth aircraft looks to a radar a bit like a disco ball: its reflections are all specular and concentrated in specific directions. Except, unlike a disco ball, the mirrors are arranged such as not to hit the observer's eye as often," In other words, an anti-retroflector.

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For military helicopters, what is the typical fatigue life of the main rotor dynamic components?
For military helicopters such as the Sikorsky UH-60 Black Hawk:
What is the typical fatigue life of these helicopter main rotor dynamic components in cycles and hours?
a) Main rotor pitch links (aka main rotor push rod)
b) Main rotor pitch change horn
c) Main rotor blades
Helicopter or Rotary Wing Terminology

you can edit your previous question instead of making a new one.

@ratchetfreak it has been Jay Carr to suggest him to split the question.

@Federico I see the other question has been edited enough, voting to reopen now

Hi Everyone, firstly thanks for you suggestions as I'm a new. Both the questions I asked are specific and focus on two different aspects of helicopter design. This question focuses on the fatigue life of dynamic components while the other question focuses on the fatigue life of airframe for military helicopters such as the Black Hawk. I was suggested to split the question which I did so. Therefore, I will appreciate your help on both these questions. Thank you.

The fatigue life of helicopter dynamic components is determined by the manufacturer based on the number of hours flown and as such, varies from helicopter to helicopter.
In general, life of the dynamic components are less than that of the helicopter structure. The life of the dynamic components depend on the fatigue loads (the magnitude and load spectrum) and the materials used.
So, the same helicopter involved in more demanding operations (civil vs. military) will have less life. Actually, during development, the fatigue life is determined in number of cycles, which is then converted to flying hours based on the expected flying pattern. Also, the materials used make a difference, with composite materials having better fatigue resistance compared to metallic blades.
The life of the UH1 MRB (Main rotor Blade), for example is around 2500 hours. For UH60 MRBs, similar values have been quoted for metallic blades. However, Studies by MBB (Now part of Eurocopter) indicate that the composite blades under normal loading have a fatigue life of around 4000 hrs (AGARD conference Proceedings No. 297, Helicopter Fatigue Life Assessment).
The life of other dynamic components, e.g. pitch horn, pitch link etc. are usually around 1000 hours. However, with little data available in public domain for helicopters under service, it is hard to say with any certainty.
It should be kept in mind, however that these values are only indicative as all dynamic components are periodically checked using NDT methods and decision on their continued service is solely based on the results of these tests. For example, any damage to the bearing in the pitch links will result in their replacement. Also, the development of Health Usage Monitoring Systems (HUMS) means that most of the H/c manufacturers are moving away from a life based approach to a health based approach, resulting in variation in life of individual components.

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Can I accept a SID if I can't make the required climb gradient on a single engine but have no problem on two engines?
Can I accept a clearance containing a Standard Instrument Departure (SID) with a climb gradient that I can easily make on all my engines but can't make the required gradient on one engine inoperative?
If I can and I lose an engine on departure what should I do so I don't hit anything?

It depends, what regulations are you operating under?  91, 121, 135, etc.?

Part 91.  Are there regulations stating differently for 121/135?

They are indeed!  Obstacle clearance requirements are different....

Depending on certain factors, you can accept a SID clearance knowing that you cannot make the required climb gradient with one engine inoperative (OEI).
The FAA Aeronautical Information Manual (AIM) 5-2-8 ODP and SIDs states this:

ODPs and SIDs assume normal aircraft performance, and that all engines are operating (AEO).  Development of contingency procedures, required to cover the case of an engine failure or other emergency in flight that may occur after liftoff, is the responsibility of the operator.

This answer begs another question and what are some contingency procedures you can consider when accepting a SID when the required climb gradient is not possible with OEI procedures?
The FAA lists two possible places for this information:

AC 120-91 - Airport Obstacle Analysis
Instrument Procedures Handbook (FAA-H-8261-1) Chapter 1.

AC 120-91 talks about how runway analysis is used to comply with Part 121 / 135 obstacle climb requirement.
Instrument Procedures Handbook provides additional information on how OEI takeoff obstacle clearance requirements are different than TERPS requirements.  Besides using runway analysis, there isn't a lot of additional information on contingency procedures.
Here are my contingency procedures in the preferred order

Runway Analysis - Let an engineer figure out the maximum weight to takeoff and be able to climb above the obstacles
Radar vectors - Once ATC issues the words "Turn left / right heading xxx°" they are equally responsible for terrain clearance
See and avoid the terrain (VMC only) - If we can see the obstacles... hopefully we can miss them.  Of course, mountains don't care if you can see them or not.  They don't move.
Obstacle Departure Procedures (ODP) using OEI calculations.
SID using OEI calculations.

It would be great if others come up with a different set.  I would love to see them.   I will typically work through this listing and if I am taking off from an airport without radar services in IMC where I do not have runway analysis, I need to be able to make the ODP or the SID on OEI performance.

In Europe and I suspect the FAA has a similar rule, if you are flying commercially, you're allowed to fly the SID...but you need to have performance documentation on the specific airport with the specific A/C, engines and runway which will give you your climb gradient single engine and an escape route to follow in case of Engine failure. Most major company have a in house doc, others will use Flygprestanda, flightGuru etc... which will compile those calculations for you.
The short answer then is :Yes you can, provided you can demonstrate that you know which path you'll followed on SE and what will be your performance.
Hope this helps ;-)

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What is an NTAP when referenced in a NOTAM?
When reviewing notices to airmen (NOTAMs) for the KDNL airport today (08 April, 2016) there's a particular NOTAM that references an NTAP with a number. What's an NTAP? How does one go about looking one up?
!DNL 03/008 KDNL SVC SPECIAL EVENT MASTER'S GOLF TOURNAMENT SEE NTAP 1604031100-1604112359

Not sure if thats the NTAP number, its formatted as a time... [20]16 04 03 11:00 to [20]16 04 11 23:59, basically April 3, 2016 at 11 until April 11, 2016 at 23:59

The Notice to Airmen Publication is an FAA publication, currently available in PDF or print form, published every 28 days. The NTAP contains airway, airport, facility, procedural, general, and international NOTAMs. As voretaq7 notes, this includes long term NOTAMs that a flight service brief won't include if you don't ask. There is also a section with graphic notices, including general notices, special operations, airport and facility notices, and major sporting and entertainment events.
That last section is the one relevant for the NOTAM listed above. This lists information and procedures for any airports affected by special events, which is nice to have in one place rather than looking up long and complicated NOTAMs for each airport. For example, the Masters Golf Tournament referenced in the NOTAM above has a section in the NTAP, affecting airports AGS, AIK, DNL, and HQU. The information includes preferred IFR arrival routings, potential for holds and VFR arrival delays, departure procedures, preferred IFR departure routes, IFR overflights, and VFR arrivals/departures to/from DNL. There is also a special schedule for the tower at AGS, and a temporary tower at DNL.

It's also worth noting that the NTAP (also sometimes referred to as "the printed NOTAMs") also includes long-standing NOTAMs that won't be read to you by a flight service briefer: You need to ask for them specifically, or review the NTAP yourself.

NTAP is the Notice to Airmen Publication. It is published every 28 days. The electronic version can be found in the faa site.

Simply enough, it is the "Notices to Airmen publication", which has the full description of the NOTAM.


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By how much did the content of the Airbus A320 FCOM expand over the last 40 years?
The Airbus A320 has been in service for almost 40 years now. I imagine that the current manuals are much larger than the manuals provided in the 80s, mainly for three reasons:

The newer models feature many more systems (EGPWS, Auto TCAS, ROPS, BUSS, ...)
The manuals were amended and refined based on accidents, incidents and shared experiences
The manuals are subject to "content creep", where both structure and content bloat up over time, as many people worked on the documents for many generations, but "old stuff" is never removed.

I would consider 1+2 healthy and 3 unhealthy. Does anyone have access to the original docs from the 80s / 90s for comparison?

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What are the pros and cons of a pulsejet?
I've heard pulsejet powered aircraft can fly at very fast speeds but are there any drawbacks to this type of engine? And are the disadvantages greater than the advantages or vice versa?

The pulse jet engine works because it uses the dynamic pressure of air for compression. Consequently, it needs speed to work well. If the pulse jet is on the ground, it is not easy to start - it needs to be fed with compressed air, and once it runs (it can run even when not moving because the oscillating pressure wave inside the tube will compress the inflowing air), it develops litte thrust.
Thrust will go up with airspeed, so you need additional thrust sources for initial acceleration and take-off. In case of the V-1, this was done by a steam catapult or by air-launching the device. Note that the V-1 was accelerated to 370 km/h on a 45 m long catapult which means more than 100 m/s² (10g) average acceleration. Most of the development work went into making the airframe withstand this acceleration. A modern design would need additional engines as well, and once those are included, the rationale for pulse jets becomes very weak. They make sense if you have an air-launched, disposable application, such as long-range air-to-air missiles. This is a niche in which their higher-speed cousins, the ramjets, will still be used.
Pros:

Very easy to build, very light.
Runs and produces some thrust when at rest (as opposed to ramjets).

Cons:

Thrust grows with flight speed. This can be seen as a pro, but normally requires additional means of acceleration. Therefore listed as contra here.
Low fuel efficiency. The fuel energy is converted to other forms of energy: Just listen to the videos of Colin Furze to get an idea.
High levels of vibration due to the intermittent operation. When the Heinkel 280 was tried out with Argus pulsejets, the aircraft experienced unacceptable vibration.
Need heat-resistant materials. The central part will get very hot in operation, so at least nickel-chrome stainless steel is needed if air cooling is insufficient.
Cannot go supersonic. For this, there are ramjets.

EDIT:
NACA tested the As 014 pulse jet and wrote a report, from which the performance data depicted below is taken:

It seems that Bruce Simpson over in New Zealand has improved the pulse jet design a lot: He needs no compressed air for starting and makes clever use of surrounding cold air to increase mass flow and keep material temperatures down.

First of all they are loud there is a reason that the V1 bomb is called the "buzz bomb".
They are also fuel hungry due to the low compression ratio.
The biggest advantage it that they are very simple. Once you have them ignited they will continue to burn until they run out of fuel or the airflow is disturbed.

not to mention that pulsejets are by far the easiest jet engines to build. there are plenty of good videos about pulsejets by colinfurze on youtube.

Pulse jets were big during WWII but the have a few issues.
Advantages:
Aside from throttle flaps pulse jets have essentially no moving parts which makes them not only simple to build but simple to maintain. People build them in their garages at home all the time. From a war time standpoint this was great since you could make many of them in a short time.
Disadvantages:
Noise: Pulse jets are much louder than their spinning counterparts. This makes them some what less useful from a stealth/wartime standpoint and from a commercial standpoint in regards to general noise pollution concerns.
Low Impulse: From my understanding of them pulse jets have a low specific impulse due to their more piston like ignition pattern. They don't deliver the kind of thrust their fan like counterparts can.
Size: If memory serves they are also much bigger than a regular jet (for a given power output).

Disadvantages:

Very low thermodynamic efficiency due to very low compression ratio.
Therefore they are not very fuel efficient.  They consume a lot of
fuel.
They are very very noisy.
Reed valves fatigue quickly.  Reed valves can also be subjet to heat
and loose their temper.  Bruce Simpson has done a great deal of work
to improve the lift of reed valves.
High temperatures involved.
Valveless pulse jets tend to be less efficient than valved (but a lot simpler).
Most of the literature on valveless pulse jets is substantially incorrect as to what is happening with the gas flow within the engine.

Advantages:

Simplicity

Pulse jets can be designed to develope maximum thrust at stand still or at any particular sub-sonic speed.  If they are designed for maximum thrust at a reasonably high speed then their stand still thrust will be low.  A low velocity pulse jet will suffer from the flame tending to be blown out the back of the engine as the forward velicity increases.  There are ways of making pulse jets so they can develope maximum thrust over a wide speed range.

Welcome to Aviation.SE!

One other advantage of pulse jets is: they are dirt cheap to build, as compared to other forms of aircraft engine. A primary reason they were used in the V1 was their very low cost.
One other disadvantage: they really have only one efficient power output: their maximum. While this does vary with airspeed, it also means that pulse jets can't really be throttled down without risking a flameout. That would make landing a pulse jet aircraft a challenging affair.
Since the V1 was never designed to make a controlled landing with a pilot on board, that wasn't an issue.


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Was the Airbus A300/A310 ever supplied with a yoke and not a sidestick?
In the Air Crash Investigation episode "Kid In The Cockpit," which details the crash of Aeroflot Flight 593, the video shows the plane had a yoke not a sidestick
I was under the impression all Airbus models, even the earlier ones, used a sidestick.
Can anybody clarify this for me?

you sir, have a sharp eye for detail! +1 :)

Perhaps we should rename the question include A300/A310 to emphasize the similarity between the types and make it past tense.

The sidestick was a design that came about along with the new fly-by-wire technology of the A320 in the late 1980's. The physical leverage of a yoke was no longer needed for flight control cables. The older designs of the A300 and A310 series planes from the 70's and 80's have conventional yoke flight controls.
I would not be surprised to see inaccuracies in TV reenactments, but the yoke did happen to be important in that particular case.

... as was the autopilot with independently disconnectable axis (no longer possible on A320+) and lack of flight envelope protection (added on A320). Also MayDay/Air Crash Investigation is usually pretty accurate (does not necessarily extend to other similar documentaries).

Great [video][1] of Azore Airelines A310 hand yoke flying over LPPD.
So yes, it did ship w/ a yoke. :)
[1]:


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Do pilots reject takeoff if aircraft doors are not properly locked down?
This particular incident, the pilot rejected takeoff "due to a aft door indication".

My questions are:

Is it a such serious situation so as to reject take-off?
If the pilots had taken off, could the crew have secured the door on their ascent?

Do you continue to drive your car if the "open door" warning light is on?

@n_b If I have physically verified that all the doors are properly closed, then yes, quite possibly. I'd still want that fixed, obviously. That said, the risk involved in driving a car at, for all intents and purposes, 0 AGL is somewhat different from the risk involved in flying an airplane at 30k-40k ft AGL.

@MichaelKjörling And how do you propose that the pilots physically verify anything outside the cockpit while they're busy taking off?

@DavidRicherby They can't, but that's pretty much my point; you can't directly compare driving a car to flying an airplane.

@n_b ... Yep! I open and close it whilst driving :D

@Cloud the extra drag allows for tighter turns, if you do it right!

@Cloud That's exactly what I would do and if it's towards the passenger side, I would ask them to close it properly.

@n_b: Once you're going at a reasonable clip, it won't matter, since the aerodynamic forces on the door will hold it shut anyways.

The crew has already secured the door just before leaving the gate, cross-checked them and the pilots saw the sensors indicate closed. So if the warning goes off during take-off roll, it is not somebody's simple mistake, but something is broken. It might be the sensor, but it might be something on the door and that might be pretty bad. So as the old saying is “it's better to be on the ground wishing to be in the air than in the air wishing to be on the ground.”
Below about 80 knots the pilots will (should) reject the take-off for almost any warning or abnormal indication they get. If the problem can be fixed easily, they can just taxi around and take off a couple of minutes later. Above that speed the emergency braking is likely to overheat the brakes, so from about that up to V1 pilots will only reject for engine failures and other very serious warnings, while for other issues they'll make the circuit and return to land again.

Your second paragraph describes the policy at the two 747 carriers I flew for. Also, though it wasn't in the op specs as I remember, it was felt that any abort between 100 knots and V1 (typically somewhere in the range of 140 to 160 knots) would be a full blown emergency.

As I understand, a lot of warnings appear in the cockpit throughout the flight. The intent of my question was to understand, that a door indication alert was a big enough reason to abort takeoff.

@Firee, no, there are normally no warnings except during preflight as either checks of the warning systems or during intermediate state when some systems are not started yet. A warning means something is really, really wrong that needs immediate correction from the pilot (a caution means something is wrong, but not as critical). In most flights you don't get any. In fact, most of the time there is very little beyond the flight and navigation instruments as indications are designed so that all lights are extinguished in the usual flight state of things.

Yes if prior to V1 (takeoff decision speed). On most modern airliners there are proximity sensors that monitor the latching system at various points, that will produce various warning or advisory messages (for example, a single sensor out of an array of several on a given door may provide only an advisory, whereas more than one sensor agreeing may produce a warning).  The more minor indications are usually inhibited during takeoff.
If after V1, the pilot will continue the takeoff (although in extreme circumstances the PF might reject after V1 if he/she hasn't rotated yet; like say there is a huge bang, and the runway is really long; it's an instantaneous judgment call).  If an advisory, during the climb-out the pilot may ask the FA to visually verify the mechanical latch indications and if ok he/she may carry on, or if a more serious warning he/she won't take any chances and will tell the FA to stay strapped in, depressurize the aircraft, and return.

Note that on a long runway, V1 will simply be equal to Vr.

"in extreme circumstances he might reject after V1 if he hasn't rotated yet" I suspect the pilots of Air France flight 4590 would have loved to use that option...

V1 is a decision point, generally selected such that, past this point, there is insufficient runway remaining to stop the aircraft.  The safest option here is to go flying, declare an emergency and return to the airport.

After V1, a pilot will only reject takeoff if they have reason to believe the airplane is unflyable.  V1 is the point at which you no longer have enough runway to stop on, so you're basically trading a crash in the air for a crash on the ground.

On 4590, a thin strip of metal cut a tire which blew up and caused the tank skin above it to rupture from the shockwave.  The crew would have heard a little thump, at most, and when ATC reported flames, they may have assumed it was the engine flaming from a bird strike would continue the takeoff.


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Is there a Cockpit Video Recorder?
Often we hear about Cockpit Voice Recorders, but are there video recorders?

What would be the purpose of them?

They're presently not in use.
The accident investigators don't generally clamor for them, since there are very few questions that they can't answer with FDR and CVR readouts, where a CIR would provide useful information.  The voices proposing them as a great idea tend to come from elsewhere -- from those who think they'd be a cool idea, but who don't fully understand the capabilities investigators already have.
Pilots are, understandably, averse to the idea -- working where your every word is recorded every minute of every day isn't thrilling, but the protections for CVR recordings are pretty strong, since only transcripts (not the actual audio itself), and transcripts edited down to relevant portions only, are all that can be released, and those only in case of accidents (at least in the USA).
Video isn't nearly so easily transcribed as audio, and any such description of moving images opens up far more possibility of subjective or dramatic interpretation of what's shown, and ample opportunity for YouTube "experts" to craft alternate - if wildly implausible - narratives. The idea of a public outcry, or an aggressive lawyer, demanding the release of the full video of a crew's last minutes, or hours, opens up the unsettling possibility that families may see a loved one's final moments in far more detail than simply transcribed words on a page.
And let's be honest, in a full day at work, who doesn't have moments that, edited down to a few out-of-context three-second clips, wouldn't paint a poor - if utterly inaccurate - picture of who you are and how you work?
Until and unless actual accident investigators build a persuasive case for the need for such technology in our cockpits, such devices are likely to remain in the realm of the hypothetical.  There is simply no evidence that they would do anything to make aviation any safer.

Nothing a well placed sticky note can't solve!

@acpilot very valid point. Unfortunately, there'd be no time to remove said sticky note when you hit a situation where a CIR would be actually helpful (if such a situation arose - Ralph makes a strong case against it - at least for now.)

Whether it will matter in an investigation is irrelevant. Those cameras would be getting covered. An uppity fed could use a small clip to cause a lot of problems for a pilot, covering the camera would probably only be a slap on the wrist..."Constant surveillance and the resulting need to perform for the camera causes my crew to focus on things other than the safety of the passengers. The constant need to worry about how they may appear their body language, and how the most innocuous gesture could be construed as an indication of incompetence is a dangerous distraction."

@acpilot Pilots routinely disabling the CVR/FDR wouldn't be a slap on the wrist offence; why would disabling the hypothetical CIR be any different?

How would anyone find out?  How would anyone know the pilots disabled the system vs it just being inop?

Air Crash Investigation (Mayday) series 18 episode 6 covers the crash of the VSS Enterprise. During the episode, it showed that investigators not only had access to full telemetry data, CVR and external cameras footage, but also views from within the cockpit, looking over the pilots shoulders
It showed the pilots operating controls, but ultimately simply confirmed the telemetry data; they already knew the feather control was unlocked and when, so added little detail.
It was interesting to see the differences between footage showing similar actions in a simulator vs that in a real flight with vibration and g-forces making pilot actions more complex.
To the question, this aircraft does have a cockpit video recorder, footage can be seen, and may have added some small amount of additional insight into this particular crash.


text:
Why are flight recorders generally located in the tail?
Is there a particular reason why FDRs and CVRs and associated similar bits of equipment are kept in the tail section of a plane?

When an aircraft is crashed, the entire front of the aircraft is expected to act as a crush zone. By placing FDRs and CVRs near the tail, the shock wave that reaches FDRs and CVRs is reduced significantly.
The probability of survival based on seating is shown in this picture:

(Image Source)
Hence one can see that the shock wave reduces as it reaches the rear of the plane. That is the reason FDRs and CVRs are installed in aircraft's empennage section.

(Image Source)

Please note that the precise location of the recorders depends on the individual plane. Sometimes they are located in the ceiling of the galley, in the aft cargo hold or in the tail cone that covers the rear of the aircraft.

And Business Class passengers actually pay for the privilege of travelling inside the crush zone.

@PieterGeerkens Shhhh! Don't tell them that.

@PieterGeerkens and this is actually a great incentive for pilots to not crash.

Maybe worth linking to articles containing the images? I was curious where the survival probabilities came from and found this Popular Mechanics article - turns out they're from crashes in the US, restricted to ones that had both fatalities and survivors, a bit misleading. (The actual blog post on the site you linked to for the image links to that article too.)

That crush-zone image might just save my life. Thanks!

@Jefromi I think the statistics in that article are quite sound. Crashes that don't have both fatalities and survivors contribute no data on the relative risk of death in a crash.

@MarchHo depends on how those percentages are sold/read: in the current state they mean "if there are survivors at all, this is where is likely to find them", but most people expect a chart saying "if there is a crash, this are your chances of survival", something you obtain including crashes with no survivors.

@Federico And it's very important to include the crashes where everybody died. The difference of 69% at the back versus 49% at the front looks huge but it might be an artifact of the data selection. As you add more and more crashes with 100% fatalities to the data, those numbers will get closer and closer together (and closer to zero).

@MarchHo Given that it has absolute percentages on it, I don't think you can really expect people to guess that it's only intended to convey information about conditional probabilities without context. (The answer just says "probability of survival", again suggesting absolute probability.)

The reason for the FDR and CVR to be located in the rear of the aircraft is because that gives the best chances of recovering them.
Usually an aircraft has a forward speed when it crashes. The initial shock of impact is absorbed by the forward part of the aircraft, resulting in a more gradual deceleration for the aft parts as the aircraft breaks up. By putting the FDR and CVR in the back the acceleration is reduced allowing for a higher probability of them remaining intact.

The tail also tends to crash 'slower' if the plane breaks up, due to the drag of the stabilisers. A minor point with regard to the major one that 'it's the place they're most likely to survive'

In addition to Farhan's excellent answer, it should be noted that reducing the peak impact shock is not the only reason that the FDR is placed in the tail, and that the passenger survivability is higher behind the wings.
The wings are full of fuel, and when the tanks rupture during a crash the fuel tends to spill forward. If you look at crash videos you will notice two common scenarios:

In incidents in which the plane scrapes along the runway, friction with the ground starts a fire. In this scenario the rear of the plane is engulfed in flames, but that is the exterior. When the plane comes to rest, either the whole vehicle is engulfed or the fire recedes to small flames on the parts touching the ground: the engines and undercarriage.
In incidents in which the plane collides with the ground and does not scrape, the fuselage and wings rupture and fuel spills forward. In these cases the fires are mostly in the front portion of the craft, and the broken fuselage allows the fire to quickly spread to the interior of the craft. These fires are much more dramatic and look like explosions due to the high quantity of fuel and fuel vapor being available.

In the USA, there is a legal requirement

(e) The recorder container must be located and mounted to minimize the probability of rupture of the container as a result of crash impact and consequent heat damage to the recorder from fire.

(1) Except as provided in paragraph (e)(2) of this section, the recorder container must be located as far aft as practicable, but need not be outside of the pressurized compartment, and may not be located where aft-mounted engines may crush the container during impact.
(2) If two separate combination digital flight data recorder and cockpit voice recorder units are installed instead of one cockpit voice recorder and one digital flight data recorder, the combination unit that is installed to comply with the cockpit voice recorder requirements may be located near the cockpit.


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Where can I find information about Boeing delivery history?
Where can I find the records of which airplane model and creation number was delivered to which airline in which year for Boeing (Like B737-300 number 32 was delivered to Lufthansa in 1980)?

Try something like the construction lists at https://www.planelogger.com/Aircraft - that will show every aircraft in order of production, and who it was delivered to, although you'll need to click each entry to see the delivery dates.

@SMSvonderTann I think this is a good question, but to satisfy those who claim the question is too broad, you might consider narrowing down to one or a few manufacturers, if that would meet your research criterion.

http://www.airfleets.net/

resources location is off-topic as defined by the help center. You'd better ask "What are the livery historically used by Lufthansa on the 737?". Good answer will provide resources for further reading.

Planespotters.net also has a nice list. It has a good layout, and has pictures.


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Is there a benefit to a pilot/aviator having an FCC GROL license?
I am an avionics technician (c-130) in the USAF and plan on learning to fly helicopters when I separate in about a year.
I have debated whether or not to pursue a GROL or possibly A&P.  From what I know, these are generally intended for maintainers/technicians rather than aviators.
That said, would there be any benefit to having a GROL or related license for an aspiring helicopter pilot?

There's no tangible benefit to having a GROL in getting a pilots license of any kind as getting the license generally confers the right to use aircraft radios. In some places you need to get an RT license for aviation as a separate test, however that's pretty minimal. A GROL is only good for repairing, maintaining, and running certain types of radio stations.
An A&P will let you work on airplanes, but it also does not help get a license. An A&P will give you insights into how an airplane works, but you can get those insights without an A&P. Having an A&P and a pilots license might be a different story if you plan to work in remote locations where being able to fix your aircraft when it breaks is useful. It won't help you get a flying job in most places.

From what I know, these are generally intended for
  maintainers/technicians rather than aviators.

Correct, an A&P will not help you get a pilots license (aside from maybe gaining a better understanding of how the internals work).

That said, would there be any benefit to having a GROL or related
  license for an aspiring helicopter pilot?

This is a bit of a different question, to which the answer may be yes, in the sense that an A&P cert can be useful if you are involved in aviation. An A&P could be very valuable to you as an aviator in general. First off if you intend on owning a helicopter you will be able to undercut some of the costs by doing work yourself. As mentioned if you intend on flying in remote places being able to work on your own bird can literally save your life. If you are looking to fly professionally you can always make money on the side doing A&P work (its a pretty high paying profession). I have no idea if it has any bearing but there is a chance it will lower your insurance premiums as well (generally the more certifications you have the lower your insurance

The only FCC license that you might need is the restricted radiotelephone operator permit (RR).  There is no test for the permit but there is a fee.  You'll only need the permit if you intend to fly outside of the united states and communicate with foreign ATC.


text:
Are cargo aircraft ever ferried empty?
If the amount of cargo is not evenly distributed across a network a freighter will sometimes have to fly a route not loaded to capacity. Do cargo freighters ever have to be ferried empty to alleviate this "back-haul problem"? The link uses the example of trucking, but my question is to what extent this issue manifests itself in scheduled air cargo (e.g. FedEx, UPS, etc.).
(Note: My assumption is that this affects scheduled air cargo operators more severely than specialty cargo operators doing "one-off" hauling of special goods)

If a plane cannot carry everything to be hauled, and delivery is guaranteed overnight, then a 2nd plane would have to brought in to handle the excess.This probably only impacts the big boys, like Fedex, UPS, DHL.

I'd expect it to be the other way round: specialty operators spend far more time flying empty than scheduled services.

Cargo airplanes are ferried empty in some situations, sure. Maintenance is a common reason, or one leg of charter cargo flights. It's pretty rare in scheduled cargo flights as it would mean there's not a single package going that direction, there's almost always something to take.

If FedEx has to get a plane from IND to MEM to get an extra load out of MEM to its destination, there will surely be packages at IND that are ready to go. Some may be next day that have already arrived, some may be 2-3 day that can go ahead and go now... I'd be willing to bet that unless it's a serious maintenance issue, the general package carriers never fly empty.

@GdD - Do you happen to have a source for how frequently this happens? I figured that it would happen along the lines as you describe, but I was hoping for some anecdotal or documented frequency (e.g. 0.3% of flights are maintenance/ferry flights)

I would expect that many of the planes transporting things like phones from China to the US would return empty or nearly so. You can also buy things from China on Amazon and the post office delvers them in a few days for next to nothing. The return postage is exorbitant. Do you have any insight into those operations?

I have no info on US-China cargo operations, my knowledge on cargo comes from a couple of EU cargo pilot friends. They do regular routes, but also special one-way operations like delivering tires for formula 1, horses and dogs to races. It's rare they go out and back, usually they will have some sort of cargo on another leg.

@FreeMan There are definitely positioning flights. I'm sure dispatch does everything they can to avoid them, but freight is not always ready to go when the plane needs to. If a flight bulks out they will have to come up with a plane somewhere. I once jumpeated on an empty DC-10 from EWR to LGA. A really short hop, but they had to fly a pretty decent distance out over Long Island to get set up for the approach. It was about 15 minutes in the air.

A nice view of NYC for sure @TomMcW, if the weather was decent.

@GdD Best view of NYC ever. It was like a tourist flight in a DC-10.

I was on a flight into LGA which was routed up the Hudson river, I was on the right side at a window, it was pretty spectacular!


text:
What does Elon Musk mean by "electric jet"?
Elon Musk has said that he has a design for a vertical take off and landing super sonic electric jet. I was under the impression that jet engines work by burning fuel, expanding volume and thus creating force. How can this be done electrically?

The fuel-burning, gas-expanding stuff is only needed to drive a turbine. If you restrict the jet to a compressor which accelerates air flowing through a duct, an electric engine will do nicely. But to build an electric, man-carrying supersonic VTOL craft is clearly in the realm of science fiction. Today's technology cannot achieve this in any meaningful way.

Also a jet engine is a heat engine, so it can run on anything that heats and expands the volume of the air flowing through it. Electric heaters would work just fine. The problem is that jet fuel has better energy density and adds mass and volume, so batteries really can't compete in efficiency. I suspect Peter might be right and Musk actually was thinking about ducted fans with electric engines. That might make sense for short hops between grid powered pads. Did he really talk about it also being supersonic?

The cynic in me is picturing the Starscream Model S - Amazing performance, but you have to stop at the 25 service stations between here and there, and don't let it strike anything lest it catch fire.

@Peter Kämpf: But how is that a jet, and not an electrically-driven ducted propeller (AKA ducted fan: https://en.wikipedia.org/wiki/Ducted_fan )?

@jamesqf: Strictly speaking, it isn't. But Jon Story's answer explains it better than I ever could. Of all the far-out ideas coming from Mr. Musk, this one is probably the most misleading one - if what has been reported about it is correct.

You can still compress air then jet it. As long as the air exit speed is higher than the intake speed then it's a jet.

Jet noun

a rapid stream of liquid or gas forced out of a small opening

A Jet Engine is an Engine which uses a Jet for propulsion. Typically, a "rapid stream of gas", in which the gas is air. Really, we could count pretty much any aircraft engine as a jet, but it depends on how "rapid" you require the air to be before it's a jet.
In a typical jet engine as we define it now, the jet is created by burning fuel and air... but there's no requirement for that to be the case. An electric jet would simply use an electric motor to create a rapid stream of air.
Would it really be a "jet" engine? That depends how fast the air is - but most people see "jet" as being a fast, powerful, reliable type of aircraft, so it's as much about marketing as anything else. An Electric Prop or Electric Plane doesn't sound as cool as Electric Jet... (Although I'd argue that ElectroJet/ElectroProp/ElectroPlane are awesome names and Elon Musk has let himself down by not using one of those names)

If we forget the vauge words "rapid" and "small" we are left with "a stream of liquid or gas forced out of an opening". This seems to draw a line between propellers than spin in open air and ducted fans which force air out of an opening.

A valid point, so yeah an electric ducted fan would probably count as a jet by that measure

I would rather ask, would it really be supersonic ? I thin that the first implentation of electric/hzbrid propulsion to commercial aviation I would rather be an electric regional TurboProp

And for supersonic application I would rather rule out the Prop alternative, it would defenetly be a ducted Fan...

As far as I understand, the use of the word jet here has no relation to the engine type, except to exclude non-faired propellers.
It is being used as a  synonym for aircraft, while keeping the appeal of modern jetliners as opposed to propeller planes, which are often considered "outdated" by the general public. This same public cannot usually tell a piston engine apart from a turboprop or even a propfan, so it is understandable.
My personal understanding or Mr. Musk's remarks is that he wants to develop a "more electric" or "all-electric" aircraft capable of both VTOL and supercruise at very high altitudes, more likely the later.
An all-electric aircraft uses batteries to store its energy, which is fed into electric propellers, fans, flapping wings or any other devices that convert it into thrust. On the other hand, the more electric approach usually keeps a fuel tank, a combustion engine of some sort and an alternator to transform the chemical energy in the fuel into electrical energy for an electric propulsion method. This is because the energy density in any type of aviation fuel is orders of magnitude higher than that of even the best modern batteries, so it's more efficient to carry fuel than batteries.

PERSONAL OPINION AHEAD
Mr. Musk is a businessman, not an engineer (he hires pretty good ones to do the engineering work, since he can afford it). So when he gives interviews, consider he's doing business, not arguing the details of his ideas.
Furthermore, while I think there is no aviation enthusiast who wouldn't love to see an operational, all-electric, supersonic, VTOL-capable airliner, the chances of it happening in the next couple of decades without some major breakthrough in fuel cell or battery technology are close to nill. Until such a thing happens, energy density will continue to keep such designs firmly in the realm of interviews and 3D renders

There are instances of interviews where Musk describes in detail what the intention is.
The aircraft's main advantage would be in his opinion, would be the ability to conduct high altitude flight in envelopes where engines requiring atmospheric oxygen to combust could not operate, thus able to move faster with less resistance.
He also talks about gimballing engines for control surfaces, and using it to have VTOL capacity.
The biggest issue right now is power density for it to even exist, but from a design stand point, I'm not sure that it would be wisest to leave your control surfaces to JUST the engines. The biggest benefits to having tails, canards etc, is that in the event of engine failure, you don't turn into a brick.
And also in higher altitudes, around (At least higher than 20km) 40-60 km, I imagine you might need RCS like control systems as backup.
But getting to the 'jet' part, I believe that it's precisely what you think of it as, a 'turbofan' with the core powered by a motor and gimballed.

But getting to the 'jet' part, well, that would be the question, all the rest is accessory information. I believe well, that does not make for a nice answer, though, do you happen to have additional sources?

If there is not enough oxygen to burn fuel, will there be enough gas to propel?

Perhaps he means an electrostatic fluid accelerator. Mr Musk or his engineers are the appropriate parties to clarify what he has in mind. It could be a turbofan without a turbine (= just a fan).
I know he has proven the naysayers wrong about electrically propelled cars, but in the matter of electrically driven, supersonic VTOL aircraft, I remain a naysayer. I would be very excited to see a more detailed and viable design.

Near as I know, this was a hypothetical proposal for an aircraft making use of gimballed electric motors, allowing it to redirect the thrust for VTOL flight operations.  As for the supersonic part, that's going to be a tall order for Musk.  So far there has only been one marginally successful supersonic VTOL aircraft put into production and that's the F-35B.  It was nearly stillborn due to weight and complexity issues, can only hover with less than 40% total internal fuel, and whether the complicated lift fan system can operate in the demands of real combat remains to be seen.  I can imagine the technical design challenges for doing all this and still making an ALL ELECTRIC aircraft as well makes me think Musks eyes are far bigger than his stomach.
UPDATE - Another idea which occurred to me about designing a supersonic VTOL vehicle like this would be a hybrid propulsion system using a gimballed electric drive ducted fan/cold diffuser for powered lift flight and acceleration combined with a chemical ramjet for high speed flight.  It would be more advantageous than an all electric system and might be possible in the near future.  It would require quite a powerful electric drive system to propel the craft up to the 400 - 500 KIAS required for the ramjet engines to become effective.
ANOTHER OPINION
After having worked in the aerospace world as a design engineer for 12 years, I'm going to give you all a little wisdom about the business.
There are a whole lot of fancy pieces of concept art and CGI in social media but little actual flight hardware which ever sees the light of day.
Airplanes are EXTREMELY complex vehicles in their current state to design and manufacturer, requiring billions of dollars and thousands of man years to bring into fruition.  Increase the complexity of that design, even in trivial ways, and you drive the costs through the roof and imperil the enterprise to be stillborn, ensnared in its own complexity.
Musk, as stated above is an entrepreneur and software whiz, not an engineer.  His PayPal system was brilliant but I can't say the same for SpaceX or his current Hyperloop boondoggle where design work seems to be pushed off to student design teams without even the slightest efforts made the real issued of designing a safe, evacuated tunnel for this thing to operate in and all with a laughably unrealistic price tag.
Anytime someone proposes such a design, ask yourself this one question:  If it was that simple, why aren't Boeing/Lockheed/Northrop Grumman/Bombardier/Sukhoi/Chengu/Textron/Embraeer/Mitsubishi designing similar vehicles for lesss as they have the economies of scale on their side for these types of projects?  This usually ferrets out the reasons why such a design won't work very quickly.

BMW did not start making electric cars until Musk productionised them. The established industry can be a tad complacent. But having said that, I'm with you in not believing that this can be done, or is even useful.

Irrelevant.  We're talking about aircraft here and not cars and THERE IS A GRAND CANYON SIZED GULF BETWEEN THE DIFFICULTY OF DESIGNING A MODERN ELECTRIC CAR AND THIS KIND OF AN AIRCRAFT.

@Carlo Felicione how about the difficulty of designing rockets and docking with the ISS, then landing them, all at half the cost of one ULA launch? I agree that the technology simply isn't here yet, but "industry isn't doing it" is a horrible reason to believe this.

Maybe there's your answer as to why the the industry isn't doing it.

@A.W.Grossbard: That is easy: You poach the best engineers from ULA, a monopoly which has grown fat and lazy on public money and let them work freely, with no lawyers and beancounters telling them what to do. ULA has paid for the training of your workforce and the infinitesimally better working conditions will let you pick whoever you want. Morale is much improved and the usual blowhards have been filtered out. For me it is surprising that they still need half the money and not less.

I just came across your answer and in particular your statement "His PayPal system was brilliant but I can't say the same for SpaceX". I am just wondering if your opinion has changed after 3 years with en eye toward all that SpaceX has accomplished within that time.

@Hans not it has not.  While I’m glad that Musk is now launching manned flights and the Falcon Heavy finally gives him a heavy lift booster, keep in mind that McDonnell Douglas beat him to the goal of ‘reusable’ boosters by 20 years.  His reusable boosters really aren’t and do not offer a substantial advantage over older boosters; you just can’t get around the realities of physics.  And yes, his hyperloop plan is still a multi billion dollar boondoggle and will not work.

Can you elaborate on your statements? 1) "His reusable boosters really aren’t and do not offer a substantial advantage over older boosters; you just can’t get around the realities of physics." 2) "his hyperloop plan is still a multi billion dollar boondoggle and will not work."

@Hans That explanation is a little larger than a simple comment can accommodate.  The basics are that the reusable boosters require extensive and expensive major overhauls in order to be restored to a flightworthy status.  Having to carry recovery fuel aboard limits payloads they can launch.  It’s just cheaper to build a throw away booster.  As to hyperloop the engineering challenges associated with making a large, evacuated system like that make it impractical, maintenance intensive and just basically unsafe.


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Does a pilot of Air Force One receive any special privileges?
I know that flying Air Force One is a position of high responsibility. I am curious to know what extra privileges, if any, come along with being the pilot of Air Force One. What extra he can do which a usual commercial/US Air Force pilot is not allowed to do (in air or on ground both)?

Your second question is odd.  Why on Earth would women not be allowed to fly Airforce One?

@Simon it's not odd at all. Women are still bared from some jobs, especially in some armies. First (USA) female pilot to go to war was in 1998 .
If you want to hire the most experienced ones, 20 year might not be enough yet; making it practically impossible as of today for them to pilot AF one .

Please keep in mind that Air Force One is a call sign (specifically, the call sign of the plane that the president of the United States is onboard, whichever that is), not any specific airframe or even aircraft type. As much else as that movie got wrong, this is one thing that the 1997 movie Air Force One actually got right.

We are in the 21th century, the second question is odd. Anyway, I don't believe that combat experience or even war experience is a requirement (that could be a big problem during peace ^^). Anyway, women have a long Air Force history, back from WWII.

@Peter "We are in the 21th century, the second question is odd." No, it really isn't. There are many jobs and roles which are considered unacceptable for a woman to take (considered such by some people, anyway), and this is in rare cases a legal restriction as well. The military being responsible for several of those rare cases, it's definitely a reasonable thought to ponder about AF1.

@MichaelKjörling. You're right. Also, what about pilots of Executive One?

OK...May be my question sounded odd but many countries still don't allow ladies on war front.
Recently India commissioned first batch of women pilot first time in history...I don't knwo about US laws but globally things are different.

AirForce One would never be at the front in a combat role.

Related, since AF1 is operated by the military

@Simon I hope to be an AFO pilot one must be a US Airforce pilot. Correct? And there are many countries who don't allow women to fly the jets. Women are allowed in Airforce but not to fly in many countries. So that was considering global condition. I also don't know if AFO had any lady pilot.

AF1 is the designation when flying on an Air Force aircraft.  Marine One is used when flying a Marine-operated aircraft, such as the White House helis. https://en.m.wikipedia.org/wiki/Marine_One

Unrelated but nuclear submarine is pretty much all boys club.

@vasin1987 not completely

First off the pilot of Air Force One may or may not not be a commercial pilot (in the FAA sense) on account of the plane is operated by the military. For example the previous pilot of AFO Colonel Mark W. Tillman has no listing in the FAA database for pilot certificates so he does not cary any civilian privileges of flight although some might.
Being in the service the pilot would carry all the privileges associated with his given rank at the time.
As for other privileges there would be nothing stopping him from receiving a free meal at a local airport diner or the such but as far as I can find they have no special privileges anywhere.
If you are asking what privileges they may have in the air that is a completely different question. They still must follow ATC procedures as any other plane in civilian airspace but the flight will undoubtably be treated in a certain way.

One special treatment is that they'll be allowed to operate within a presidential TFR ;-)

I have heard that they clear themselves for take off (by informing the tower controllers).

I saw a documentary on discovery covering AFO when Bush flew to Iraq war zone then AFO didn't follow ATC rules (it was due to keep secrecy of mission). But on the same point no other flight can give false info to ATC

In the movie Airforce one ATC clears AFO to take off. Don't know what is the procedure.

The couple of times I've heard AF1 on an ATC frequency, they received clearances like any other aircraft.  (The big difference being, they probably never had to argue with ATC to get what they wanted!) But if Tower knows that there is traffic a mile off the end of the departure runway, it's probably better for everyone to hold AF1 until the traffic is clear, instead of them blasting off with an attitude of "I'm AF1, I do whatever I please!" Those conflicts are probably really, really rare, but typically AF1 mostly uses the same vocabulary with ATC as the rest of us do.

@lovegupta In the movie, when Air Force One is being cleared for takeoff, they are also at the Moscow International Airport. Well aside from the fact that what's accepted in the US (due to the fact that the plane is being operated as part of the US Air Force) might not be accepted elsewhere, plain and simple common courtesy and self-preservation instinct would suggest that you ask if it's okay before you get a 375,000 kg MTOW, 70 by 60 meters aircraft even onto a runway. Though compare Can a pilot take off at his own discretion?.

@RalphJ Well, this was in Daytona many years ago, and there are Presidential TFR's, so I'm sure that they would be well aware of any intruders that would be in the area.

I believe it's normal for traffic to be completely halted on the ground and kept well clear of the airport while AF1 is moving, so there shouldn't be traffic a mile off the departure.


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Why does wingwalking use only biplanes?
Wingwalking is an aerobatic discipline with shows such as this one.
The definition of wingwalking from Wikipedia gives no other alternative than using biplanes:

Wing walking is the act of moving along the wings of a biplane during flight [...]

(source: Wikipedia, as of 26 February 2020)
When searching for images on the web, I can only find biplanes, mainly stearman but also other biplanes.
For me, it seems that any aircraft with high wings or parasol wings can do the job, so why do they only use biplanes?

I'm pretty sure I saw a monoplane wing walk at Oshkosh when I was a kid, but it is rare.

@GdD why is it so rare? I cannot find any occurrence in the last three decades.

I don't know, but I suspect a high wing keeps the walker out of the rudder's airflow.

Perhaps walk on biplan is more easy than on monoplane!

3 reasons:

The really obvious one; biplanes had the interplane structural network to hang on to when doing the wing walking.  It's a heck of a lot safer for the wing walker.  Even today, most of the wing walker acts use Stearman or Waco biplanes.
They generally have lower wing loadings than comparable monoplanes so could fly slower.
They were readily available as WWI surplus in the 20s when the whole Air Circus business was getting underway.  Equivalent monoplanes would be new production and much more expensive to acquire.

So while there are/were monoplane wing walker acts, they weren't true "wing walkers". The original wing walkers walked out from the fuselage to the wing tip, and the usual trick on the Jenny was to get down and hang from the wing tip protector hoop that extends down below the interplane struts.  It was only possible on a biplane because there was structure and wires to hang on to.
The monoplane acts are great stunt acts, but they aren't true wing walking acts because no, you know, walking along the wing, goes on.  They have a brace to let someone stand up above the fuselage, but you won't see any of them walking out along the wing to the tip without any kind of aids, as you do on a biplane.

The interplane bracing is the wrong side of the wing, beneath their feet where they can't reach it.

@Guy Inchbald Look at any wing walker act on a Jenny or such from the 20s.  They are moving between the wings hanging on to the rigging, not along the top one.

Yeah, any realistic wing-walking requires some sort of rigging to hold onto, at least intermittently.  In the pictures of monoplane walkers that rigging has been added specifically to enable the walking.

One more point for biplanes: there are many more biplanes with the combination of open cockpits (necessary for the acrobat to get into and out of a seat for takeoff and landing), aerobatic capability, and slow flight than there are monoplanes.  Additionally, today, the look of the act is heavily tied to biplanes.

@JohnK. True that a minority do that (in fact the very first to wing-walk did, back in 1913), but it is hardly "the really obvious one" for the majority of wing-walking.

Plenty of monoplanes (albeit mostly early ones) also have bracing struts and wires on top of the wings.

@ZeissIkon: So a door wouldn't work?

It's an obvious one when it comes to the advantage of using a biplane.  Try walking out to tip of the wing of a monoplane even one with bracing wires going half way out, without special modifications.  A Jenny didn't and only cost a couple hundred bucks.

@sean Getting from a side door to the top of the wing is difficult and hazardous -- especially since many wing walkers, to add spice to the act, don't (or claim not to) wear a parachute (and it's killed more than a few -- part of the risk of the job).

I'd offer that it's due to the speed of the plane. I have seen it done with mono-wing planes as well, but it's rare, as others have also mentioned. The rationale for biplanes is likely twofold:

There's a nostalgia element to be considered, now that the style of plane is out of fashion, and has been for some time.
Two wings means more aerodynamic lift. The additional weight in the plane or just the stress on the plane itself combined with lower airspeed means that the plane needs all the help it can get to remain airborne, especially when stunts are involved.

"Two wings means more aeronautical lift."  Errr, what?

@MikeBrockington: Presumably he meant "more aerodynamic lift".  Which is true - a biplane's greater total wing area does provide more lift than that of a monoplane of equal wingspan, chord length, and wing shape (although, due to interference between the airflow around the two wings, nowhere near the twice-as-much that one would intuitively expect).

thanks @Sean, yes. that's what I meant. I just jump into different SE forums from time to time to learn about things I'm not normally into.

@Sean  But what advantage to wing-walking does a shorter wingspan mean? Due to the intimate relationship with drag, no plane is going to have significantly more overall lift than it needs - they are designed for a specific payload, regardless of one wing or two.


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Why does An-225 have anhedral wings though it is a cargo aircraft?
What are the rationale behind this anhedral high mounted wing configuration? Is that usual for very large carge aircraft?

Being definitely an [tag:ultralight] guy, I ask for this time a question related to a huge one :-)

i think that the effect is exaggerated on the ground, wings will flex upwards in flight. http://i.imgur.com/lqN2xaW.jpg

I guess cargo is usually less whiny than passengers about (ins)stability

Do you want to go out there and try to hold up that wing which includes three engines?  as @Thunderstrike says, the wings flex upwards in flight.

Anhedral wings will induce roll instability and improve roll maneuverability.
In a large/heavy airplane with a high-wing configuration there is usually excess roll stability, so this type of wings can be pretty common.
Both the high wing configuration and wing sweep contribute a negative sideslip-induced rolling moment, and anhedral is necessary to limit this moment. If sideslip causes strong rolling, the aircraft will have a tendency to dutch roll.

+1. The C5 Galaxy is another aircraft with a noticeable anhedral.

So it's a matter of trade off between stability and maneuverability?

Exactelly. It's the matter of anhedral vs. dihedral, of roll maneuverability vs roll stability, of dutch roll vs tendency to spiral dive. Most of aerodynamic design is trading one benefit(or penalty) for another

Even not so large high-wing aircraft have significant anhedral. For example BAe146/AvroRJ.

@JanHudec: Or take the Harrier (-12° anhedral). Or the F-104 Starfighter (here it was the high vertical which necessitated anhedral).

Yes, this is common in heavy cargo haulers.
As you probably are aware, a dihedral wing configuration provides roll stability. Roll the plane, and it will naturally roll back to level. A center of mass well below the center of lift provides the same effect. Put a lot of weight down below the center of lift, and you'll get the roll-back effect again.
While that's nifty, you can get too much of it. Too much stability makes the plane very hard to turn or otherwise control. You can also get a sort of aerodynamic pendulum-like effect called a "Dutch roll" as the "roll back" action over-corrects and causes a swing back the other way, and back and forth with a combination yaw and roll that is surprisingly effective at inducing air-sickness. Putting an anhedrial angle on the wing counteracts the "too-much-stability" problem created by the weight distribution, making the plane easier to control again and reducing unwanted oscillations.
Why not just make the wings lower? That may solve the stability problem, but it would create other problems as well. Just how low would the wings have to be? Would that design affect safety for ground operations or unpaved runways? And what about cargo -- how well does your new design perform in empty versus loaded configurations? How tall would the landing gear have to be to make such a design safe... and how does that affect loading and unloading?
Some aircraft, even the comically large Airbus A300-600 Super Transport "Beluga", opt for the low-wing solution, which invariably leads to a dihedral.

Airbus A300-600ST - photo credit: Airbus
But in certain cases, the high-wing plus pronounced anhedrial design has won out for some heavy cargo hauling designs, and is particularly popular with military where they may have to operate out of dirt runways and need to get the wings up away from the ground, and where short landing gear is desirable.

CG Galaxy at takeoff -- Photo Credit: USAF

The best explanation so far. Just keeping the gear short is mainly important to make loading easier; An-224 is too heavy for unpaved runway anyway.

Sorry to disagree, Jan, but Radu has my vote this time. Dutch roll damping is the main reason for anhedral with high-mounted wings. Once you start yawing, the low fuselage helps to roll the aircraft, so roll maneuverability is not the issue.

@PeterKämpf dutch roll is yet another side-effect of excessive stability. You can solve it with several options, but anhedral wing mounting is the one that keeps the wings up high. Other planes, like the airbus a380 have low-mounted wings with a dihedral, and still no dutch roll.

@tylerl: Sure, that is due to the fuselage influence on wing clbeta. The Antonov has high wings so tanks can drive all the way through, and the 380 has low wings so it looks familiar to passengers, although it would have benefitted from a mid wing configuration. The fact stays, the 225 anhedral is mainly due to dutch roll damping.

As far as I (or Wikipedia) know, freighter version of A380 is planned, but not in service anywhere yet.

@JanHudec My mistake. Had a few aircraft confused. Switched example to the A300-600ST, which is a better example anyway.

As for high-wing designs without anhedral, the difference is not in size, but in wing sweep. ATR72 does not have anhedral, similarly sized BAe146/AvroRJ does. Because the former has unswept wing and the later swept and swept wing also increases stability.

The Beluga isn't a good example either. No explicit dihedral/anhedral design choice was made for the Beluga, as it is a variation of the original A300. To ease certification , as much as possible was left untouched, thus giving if the same wing configuration as the original A300.

The anhedral is rather exaggerated in the top photo.
If you look for pictures of the Mriya in flight the wings are more-or-less level. On the ground, fully fueled, the wings with 3 engines each are heavy and will bend down a very noticeable amount. The B-52 has a similar issue, to the point where it has outrigger wheels near the end of the wings to keep them from scraping the pavement.

If you could find a picture illustrating this point I think that would be very helfpul.

@JayCarr b52 landing with 1 wing wheel on the ground: http://cdn-www.airliners.net/aviation-photos/photos/1/0/8/1400801.jpg

I would rather say the wings are flexible to some extent but not rigid ones.

@JayCarr my complements on the photo

@menjaraz ALL aircraft wings are flexible. Rigid wings tend to break. Heavy plane -> bigger bend.

@paul longer wing->bigger bend (given the same internal structure of course, stiffer design->less bend). Overall weight of the aircraft is irrelevant. See the U-2 for example.

Yep, the U-2 was flying tinfoil. I should have said "heavier load -> bigger bend". Brain got stuck in Cessna vs. monster cargo hauler mode.

Re "If you look for pictures of the Mriya in flight the wings are more-or-less level."- -I have a hard time believing this, given the geometry that we see in the photo in the original question.  Note the photo for this related answer https://aviation.stackexchange.com/a/50603/34686.  Pay special attention to the outer few feet of span of each wing, near the wingtips.  We see that portion of the right wing nearly leading-edge-on, while we have a good view of the undersurface of the corresponding portion of the left wing.  That's a strong anhedral geometry in flight.  (ctd)

(Ctd) "That's a strong anhedral geometry in flight." -- even with the extra weight of the shuttle on its "back" which if anything would tend to bend the wing closer to level, or maybe even bend the tips upwards.  But that's not happening-- the wing is maintaining an anhedral geometry.  A head-on view of the aircraft in the exact same situation would show a pronounced anhedral geometry of the entire leading edges.

Both the high wing location and sweepback increase roll stability. Too much roll stability not only reduces maneuverability but is likely to lead to Dutch roll, so anhedral is added to compensate.
Airplanes with high but unswept wings generally have neither anhedral nor dihedral.
Edit: Here's a discussion of stability, dihedral and Dutch roll, albeit in the context of RC gliders.

It is not unusual for a dedicated cargo plane design to have a high mounted wing design. It allows for the fuselage of the plane to sit lower on the tarmac while maintaining the ground clearance for the engines and wingtips.
It also makes it easier to allow the cargo door to be opened in flight without compromising the structural integrity because the main strength of the fuselage comes from the spine in the top where the wings and tail attach to.
Looking at the list of military transport aircraft, most use the same wing design. The only exceptions are those based on a civilian aircraft.

You've overlooked the "anhedral" side of the question. Is it really so or not as argued @MikeFoxtrot?

@menjaraz on ground, especially for large wings, the angle is always different from the flight one, but, afaik, the angle is measured and defined on ground.

The wing is so long that it will bend significantly when lifting forces are applied. Therefore an initial anhedral angle is present to correct for some of this bending, as without it the resulting dihedral in high lift situations would be excessive and would cause a lack of roll control.

Part of the reason for using an anhedral wing on cargo aircraft is that at speed, the wings lift and are straight out. If you look at the B-52, the wings are so long that even though they need the outriggers when on the ground, the wings flare up while in flight.

That may very well be true of the B-52 at heavy loadings, but not of many of the Antonev aircraft with their very pronounced anhedral. See in-flight photos.

It is interesting that the some of the lightest aircraft in the world-- flex-wing hang gliders and powered "trikes" -- have a similar anhedral configuration to the massive An-225.  The reason in the case of the hang glider is to maintain good roll response even in the presence of sideslip due to adverse yaw.  I.e. to keep the wing's overall "effective dihedral"-- the roll torque generated by sideslip-- close to zero in the part of the flight envelope where handling is most critical, despite the fact that the swept-wing or delta-wing geometry contributes a dihedral-like roll torque in the presence of sideslip.
In a modern hang glider, the pilot is freely hanging by a strap connected near the CG, so when he is not exerting a force with his muscles his weight effectively acts at the CG, so there is neither the "pendulum effect" (CG well below center of drag of wing) nor the aerodynamic interference between the fuselage and wing (see https://www.av8n.com/how/htm/roll.html#sec-other-slip-roll ) which contribute to shift the "effective dihedral" in the positive direction in a high-winged aircraft like the An 225.
With a modern cargo jet adverse yaw may be well-controlled by other means, but too much "effective dihedral" (slip-roll coupling) due to sweep, low CG, and high wing placement still could create unpleasant handling in strong crosswinds, and could contribute to Dutch Roll oscillations.  There could also be adverse consequences if the pilot failed to prevent the aircraft from yawing sideways to the airflow upon loss of power from one or more engines.  (See related comment within this answer to another question -- https://aviation.stackexchange.com/a/56481/34686 )
When thinking about roll stability, it is important to remember that slip-roll coupling -- i.e. positive "effective dihedral" -- is a key part of roll stability and is the reason that a high-wing plane will tend to be more stable (or less unstable), in terms of roll stability or spiral stability, than a low-wing plane designed with the exact same physical wing shape including dihedral angle.  The high-wing will also be easier to maneuver through banked turns using the rudder alone, via slip-roll coupling.  (A fun exercise to try -- ask yourself "could I land this plane if the control yoke fell off?)  But the high-wing plane will be less pleasant to handle in strong gusty crosswinds, and will suffer more of a roll rate penalty if the pilot doesn't use the rudder properly and allows the aircraft to adverse-yaw and sideslip while entering a turn.

If I am not mistaken, previous answers state that a high center of mass destabilizes the aircraft, which can be circumvented by the anhedral desing of the wings.
In such situation, it must be reminded that the An-225 was designed to carry the russian space shuttle buran !

Vertical position of the centre of mass does not actually have any effect on stability. Adding cargo on the roof does have effect on the yaw-roll coupling though do to the drag of that cargo though.

Is it easier to balance an object by holding it from underneath, or by holding it from the top?  Interesting to note the mythical pendulum is still alive in returning a rolled aircraft to upright.  But lowering CG may also have an aerodynamic effect in a side slip by presenting more area above CG.  Sort of a trade off, easier to start roll, more of a tendency to return to upright.  Adding more area beneath CG lessens aerodynamic tendency in side slip to roll, as does anhedralling.  But the mighty Antonov does have quite a bit of sweep too!

One might try to render the shuttle weightless at cruise speed by setting its pitch just right!  But low and slow, I would imagine they would keep it super coordinated.  While back someone posted CG specs for 747 shuttle carrier.  They seemed very strict for pitch too.


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How does a constant-speed propeller work?
My explanation of how a constant speed propeller works has always been a little shaky. I know about the "speeder spring," "counter-weights," and how it utilizes the engine oil pressure, but I'd love to know of a simple and easy-to-understand diagram and explanation that I can use to really understand it, and then teach it to others?

To keep it simple, the constant speed propeller has a control that the pilot uses to "ask" for a specific RPM. If the actual RPM is higher, the control system will increase the pitch. This makes the propeller taking more power from the engine to make thrust. As the engine is set at some power setting through the RPM will decrease. Works the same way in reverse if the RPM is lower than asked for.

Before we get started, I should mention that the most basic constant-speed propellers were driven by balancing air pressure and centrifugal force. The blades were shaped in such a way, or equipped with a counterweight that would cause the blade to intrinsically move to a shallow pitch. However, when air was moved over the blade, it would begin to overpower the counterweight and push the blade to a higher pitch. It's a pretty ingenious design that meant that the prop would automatically be at a high RPM when the plane was moving slowly (takeoff, landing, climbs),  and would automatically move to a higher pitch when the plane sped up for cruise. There is even a single-bladed propeller that utilized this design very efficiently for light aircraft. The problem is that this type of propeller is not pilot-adjustable, and I am assuming you are wondering about adjustable props, so that's what we'll talk about from here on.
In the first picture, observe that the pilot valve is resting directly on the flyweights (separated by a bearing). The second picture better depicts the valve system. So we see that the speeder spring is pushing down on the top of the pilot valve's shaft, which is in turn resting on the flyweights.
First off, the flyweights are turned by the crankshaft, so any change in engine RPM is immediately reacted to.
There are a few ways that the propeller is attached to the piston, and a rack and pinon type gear system is common and easy to imagine. The rack is fixed to the piston so that when it moves, the prop blade's pinion gear is rotated and thus the blade is rotated. Another common type uses a peg that is offset from the center of the blade's circular base. When the piston moves, it pushes or pulls on the peg and because the peg is offset it causes the blade to twist.
Overspeed: When your airspeed increases.
When the RPMs increase, the centrifugal force causes the flyweights to want to spread apart in order to conserve momentum. Because they're in an L shape and have a hinge in the corner, this causes the lower part to rise up, pulling the pilot valve up and compressing the speeder spring. When the pilot valve is raised, pressurized oil from the pump is allowed to flow into the prop hub through a tube that passes through the center of the hub piston. The oil fills a cavity in front of the piston, pushing it backwards. The prop blade is rotated to a higher pitch (closer to feather) which slows the engine RPM. When the RPM is reduced, the flyweights will be under less centrifugal force, and the speeder spring will push them back to equilibrium (on-speed), pushing the pilot valve back down to block the hub oil tube from gaining or losing oil.
Underspeed: When your airspeed decreases.
When the RPMs decrease, there is less centrifugal force acting on the flyweights. Due to their shape as described earlier, they are no longer able to push up on the speeder spring with the same force as before, so the compressed spring will begin to expand. This brings the top of the flyweights in, and their bottoms down. When their bottoms move down, the pilot valve moves down as well and unblocks the hub oil tube. Positive oil pressure in the hub and the blades' built-in tendency to want to move to a low pitch pushes the oil out of the hub and back into the oil system. The piston moves forward and the blades rotate to a low-pitch condition. The flyweights do not necessarily return to equilibrium, especially if you manually set the spring to maximum compression with the prop lever: you want the prop to stay at minimum pitch no matter what.
Loss of oil pressure:
Oil pressure is constantly pushing against the bottom of the pilot valve, trying to force it upwards. The speeder spring is resisting, and while the flyweights are on-speed, the whole system is in equilibrium with the valve blocking the hub tube. When you lose oil pressure, that pressure is no longer holding the valve up and the speeder spring will win, pushing the valve down and allowing the oil to flow out of the hub. This resets the prop to the low-pitch climb setting, giving us maximum power because that's more useful than maximum speed in the emergency situation that is probably about to occur.
So why do we do this?
All propellers are set at a pitch. Theoretically, a propeller is pitched to move forward a certain distance each revolution, just like a screw moving through wood. But unlike wood, air is fluid and difficult to grip. If you imagine screwing a screw into a board, the only way to make it go in faster is to turn it faster. This is because the screw's pitch is fixed. If you could space out the rungs on the screw (increase the pitch) the screw would move through the wood faster but it would become much harder to turn.
An airplane's propeller works much the same way. When we first take off, we need to impart maximum power into the air and it doesn't matter if we don't move forward very far for each revolution, because we're not going very fast anyway. We just want to move as much air as possible. But we will reach a certain point where the only way to speed to is to increase the number of prop revolutions, and that's impractical with our engines. The only alternative is to change the pitch of the blade. We change it to a pitch which allows us to move forward a greater distance with each revolution, in exchange for less power being imparted into the air each revolution. Luckily, we don't need to pump out so much energy, just enough to keep us from slowing down.
If you like numbers, imagine we have an engine and propeller that theoretically (at perfect efficiency) moves forward 1 foot for each revolution, and it can make 1 revolution per second, giving a maximum forward speed of 1 foot per second. That's perfectly fine when we're taking off: we might be moving forward at 0.5 fps, and we have some air being blown backwards a 0.5 fps. When when we level off at cruise, we're stuck at 1 fps. But we want to go 3 fps and we know our airframe can handle it. The easiest option is to turn the engine three times as fast, but unfortunately that would send some pistons flying out of the cowling. So we have to change the prop pitch to one that moves forward 3 feet for each revolution, that way it's still turning at the same rate, but it will move us forward three times as far. Or more likely we're still going 1 fps but only 1/3 RPM and burning 1/3 the fuel! It's here that you can see the issue: if we're burning 1/3 the fuel, we're only imparting 1/3 the energy into the air through the prop, and there's no way we could climb or accelerate quickly (if at all) at that setting.
A final way to think about it is just like the gears on a car. Your transmission allows you to, at 1500RPM, go 10mph or 60mph or any speed in between. The problem is that if you try to accelerate from 10mph to 60mph while maintaining 1500RPM, it will take a much longer time than if you were to bump it up to 2500RPM. High gears are great for cruising and maintaining speed, but are not great for accelerating. They allow you to keep your RPMs low, your torque low, and your fuel burn low, because you don't need that extra energy. A high prop pitch is exactly the same.
A note about multi-engine aircraft:
They are just the opposite of singles. Where singles require positive oil pressure to increase blade pitch, multis require positive pressure to decrease it. This is because in a multi, you want the propeller to feather automatically if you lose oil pressure (because of an engine failure). This removes a significant amount of drag from that side of the aircraft.
They are equipped with either a spring or a nitrogen charge in the hub that is pressurized, pushing the hub piston back to the feathered position. The prop governor works the same way but the pilot valve directs oil to push against the back of the piston, moving it forward and compressing the spring/nitrogen, moving the prop to a lower pitch.
Some are also equipped with an unfeathering accumulator. This is a bottle with a piton in the top (also charged with nitrogen) that fills up with oil when the engine is running. When you bring the prop out of high RPM, the bottle is sealed off from the rest of the system. If you lose oil pressure, the prop will feather like it's supposed to, but there will still be pressurized oil in the accumulator. That way if you manage to get your engine issues taken care of, you can push the prop lever full forward, open the valve to the accumulator, and the pressurized nitrogen will force the oil out of the bottle to put the whole system under positive pressure for a few seconds. This positive pressure moves the hub piston forward and unfeathers the prop.
Now you might think "If multis feather when they lose oil pressure, why are all those twins out on the ramp sitting there with low-pitched props?" Well, they have centrifugal locking pins that disappear when the engine RPM is high enough. If it gets low, they will fall back down into a groove around the hub piston or its shaft and lock it into a low-pitch state. This is not a fool-proof system, however, because the pins have been known to stick, and people have been known to shut the engine off with the prop lever less than full-forward. In that case you either need to get some strong guys out there to manually twist the prop back, or you need to waste a chunk of your starter's precious life turning the engine over to create oil pressure to unfeather the prop. Most engines can not start in a feathered state due to the huge drag from the blades being perpendicular to their direction of rotation.
On turboprops:
Although it can vary engine to engine, turboprops use similar systems to multi-engine aircraft but at much higher pressures and with the ability to enter beta mode (reverse pitch). That introduces problems mainly in that the engine will very quickly overspeed with the blade pitch is 0 and the prop is generating no thrust/load. I'm not going to attempt to explain it because I've never really worked with one. This guy seems to do a good job, though.

"When you lose oil pressure, that pressure is no longer holding the valve up and the speeder spring will win, pushing the valve down and allowing the oil to flow out of the hub. This resets the prop to the low-pitch climb setting," - If I'm not mistaken, this is only true for singles -- multi engine props usually feather at the loss of oil pressure to not induce excessive drag.

This is exactly what I was looking for! Thanks! I especially found the analogy to the screw going through wood helpful. @roe, my intent for the question was for a single-engine airplane, but I appreciate the knowledge that it is different for multi-engine set-ups.

@roe - Yes, you're right I forgot about multis, I'll add that in.

Where were you when I asked my question about this? :-)

@Lnafziger I didn't know this place existed until someone posted on Reddit earlier this month, or I would have been here sooner! But you guys ask some hard questions sometimes.

Don't take for granted that the light twin you fly has an unfeathering accumulator.  It is not required to be there and not all props are so equipped.  Particularly keep this in mind if you intend to practice engine out ops involving a full shutdown and feathering (with accumulator you push the prop forward and the engine will restart, without you need to use the starter for the restart).

@casey - Never seen one without one, I changed the post to "Some have."

@StallSpin no problem. Some of the older (1979/1980) seminoles I used to instruct in did not have them.